#include <iostream>

class singleton {
 private:
  /* data */
 private:
  singleton(/* args */) = default;  // 构造函数私有化，外部无法创建singleton对象
  ~singleton() = default;
  singleton(singleton&) = delete;                   // 拷贝构造函数
  singleton(singleton&&) = delete;                  // 
  singleton& operator=(const singleton&) = delete;  // 重载
};

int main(int argc, char const* argv[]) { return 0; }
